We plan to extend our experiments of simple and mixed bile salt micelles employing quasielastic light scattering spectroscopy with particular emphasis on the following: (1) The kinetics of cholesterol and cholesterol-lecithin precipitation from supersaturated model systems of bile salts-lecithins-cholesterol-aqueous solvent; (2) The characterization of the micellar properties of bile salt mixtures (designed to mimic the average composition of native bile)-lecithin-cholesterol and comparison with hydrodynamic size measurements of native gallbladder and hepatic bile; (3) The solution properties of bilirubin IX alpha and biliverdin IX alpha in terms of self-aggregation pKa values, mixed micelle formation with biliary micelles and precipitation with alkaline earth metals; (4) The physical-chemical characterization of canalicular membranes from rat liver and their dissolution by bile salt systems. BIBLIOGRAPHIC REFERENCES: Carey, M.C. The apparent critical micellar concentrations of bile salt-lecithin micelles: Influence of lecithin chain length, composition, sodium chloride concentration. Proceedings of VIIth International Congress on Surface Active Substances, Moscow (N.S. Nametkin, ed.) In press, 1977. Mazer, N.A., Carey, M.C., and Benedek, G.B. The size, shape and thermodynamics of sodium dodecyl sulfate micelles using quasielastic light scattering spectroscopy, in "Micellization, Solubilization and Microemulsions" (K.L. Mittal, ed.) Plenum Press, New York. In press, 1977.